MC908JB16DWE Datasheet, PDF (179/332 Pages) Freescale Semiconductor, Inc – Microcontrollers

Universal Serial Bus Module (USB)
The receiver features an input sensitivity of 200mV when both
differential data inputs are in the differential common mode range of
0.8V to 2.5V as shown in Figure 11-12. In addition to the differential
receiver, there is a single-ended receiver (schmitt trigger) for each of the
two data lines.
Differential Input voltage Range
Differential Output
Crossover
Voltage Range
–1.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 5.5
INPUT VOLTAGE RANGE (VOLTS)
Figure 11-12. Differential Input Sensitivity Range
11.7.2.3 Receiver Data Jitter
The data receivers for all types of devices must be able to properly
decode the differential data in the presence of jitter. The more of the bit
time that any data edge can occupy and still be decoded, the more
reliable the data transfer will be. Data receivers are required to decode
differential data transitions that occur in a window plus and minus a
nominal quarter bit time from the nominal (centered) data edge position.
Jitter will be caused by the delay mismatches and by mismatches in the
source and destination data rates (frequencies). The receive data jitter
budget for low speed is given in Section 20. Electrical Specifications.
The specification includes the consecutive (next) and paired transition
values for each source of jitter.
11.7.2.4 Data Source Jitter
The source of data can have some variation (jitter) in the timing of edges
of the data transmitted. The time between any set of data transitions is
N × T_Period ± jitter time, where N is the number of bits between the
transitions and T_Period is defined as the actual period of the data rate.
The data jitter is measured with the same capacitive load used for
maximum rise and fall times and is measured at the crossover points of
the data lines as shown in Figure 11-13.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Universal Serial Bus Module (USB)
Technical Data
179